Individuals with chronic renal insufficiency (CRI) represent a large and growing segment of our population, with much of the recent growth fueled by the increased incidence of diabetes. The adverse impact of cardiovascular disease (CVD) in the end stage renal disease (ESRD) population has its beginnings earlier, during the course of CRI, but associated risk factors have not been completely characterized. The overlap between several CVD and renal disease risk factors suggests interactions between CRI and CVD that are not completely understood. The primary goals of the Prospective Cohort Study of Chronic Renal Insufficiency (CRIC) are to determine the risk factors for accelerated decline in renal function and to determine the incidence of, and identify risk factorsfor, cardiovascular disease in the CRI population. The proposed Chicago-CRIC Consortium is a group of closely tied institutions with a history of previous collaborations, serving a geographically compact and densely populated area, serving an adult patient population of several million among which an estimated 96,000 have CRI with GFRs in the range of 30-70 ml/min/1.73m2. Using our previously effective strategies in recruiting for theNIH- sponsored African American Study of Kidney Disease and Hypertension (AASK) and MEMO trials, we will recruit and retain 500 men and women with chronic renal insufficiency (CRI) from patients served by Chicago-CRIC institutions. The Chicago-CRIC Clinical Center will provide yearly Comprehensive Visits for six to seven years, which will include 125-iothalamate GFRs, blood pressure measurements, anthropometries, urine and blood testing, and cardiovascular imaging (electron beam tomograpy [EBT], echocardiography, and carotid ultrasound). In addition, we will provide regular morbidity and mortality follow-up, which will include the tracking and classification of renal and cardiovascular endpoints. The strengths of the Chicago-CRIC Clinical Center are the established history of collaboration between the member institutions, our experience as investigators in two previous large NIH multicenter clinical studies involving renal patients (AASK and HEMO), the utilization of an existing, NIH-funded General Clinical Research Center (GCRC) for all study visits, and our ability to access databases containing a very large CRI population.